Recording device



Oct. 11, 1938. H. E. HOLLMANN RECORDING DEVICE 5 Sheets-Sheet 1 FiledJan. 8, 1936 fizz/ ezzzar: Haas Erich Hellman Oct. 11, 1938. 5 HOLLMANN2,133,140

RECORDING DEVICE Filed Jan. 8, 1956 5 Sheets-Sheet 2 FIG. 2

liwezaibrx ,fians Erik}; Hollm mm Oct. 11, 1938. H. E. HOLLMANNRECORDING DEVICE Filed Jan. 8, 1936 5 Sheets-Sheet 3 A fie/we FIG. 5

HOIZJ Eric/Q Hell/mum y Patented Oct. 11, 1938 UNITED STATES"Application Jam, a, 1936, Serial Na. In Germany December 29, 1934 11Claima; (01. res-2.06)

The present invention relates to electro-cardlographs and moreparticularly to an improved system for and method of producingcardiographic records. I

As is well known, electro-cardiographs 'depend for their action on theminute potential variations produced in the human or animal organism bythe exciting action of the heart. .By recording these action potentialsor currents tapped from different portions of the body such as betweenthe limbs as continuous curves. by means of an electric oscillographsuch asan electro-magnetic mirror oscillograph or a cathode rayoscillograph physicians are enabled to draw valuable conclusions on thepropagation of the exciting action and other conditions of the heart ofa patient.

In measuring and/or recording the voltage in the heart, it is found thatthe voltage varies according to the direction of theaxis of the heartwhich latter further changes during a heart beat cycle, so that it hasbecome customary to secure various simultaneous combinations of readingsof voltages between different points of the body, such as from, the leftarm through the heart to the right arm, hereinafter referred to asaction voltage or derivation I; from the left arm to one of the legssuch as the left leg, hereinafter referred to as action voltage orderivation II; and from the right arm to the left leg, hereinafterreferred to as action voltage or derivation III, or between any otherpoints of the body such as between diiferent points of the patient'sbreast with theheart' in.the center. By simultaneously recording two ormore action voltages upon the same viewing screen and/or record stripand in relation to the same time axis, both the magnitudes and phasedifferences between the instantaneous potentials of the action voltagesduring the individual heart beat cycles may be studied and valuableinformation obtained about the function and anatomical condition of theheart. Q

For the simultaneous recording of two or more action voltages orderivations a corresponding number of recording devices are required.Moreover, the action potential variations obtained are extremely weak,thus making it necessary to use a'separate amplifier to increase thepotentials sufficiently so as to effect a deflection of the recordingbeam such as the light beam in a mirror type oscillograph or theelectron beam in a cathode ray oscillograph.

While the improvements of the present invention are primarily useful forcathode ray oscillographic systems they may be employed with equaladvantage for any other type of oscillograph, such as a mirroroscillograph. Special advantages are obtained when using a cathode rayoscillograph as a recording devicedu'e to the 5 fact that a cathode rayoscillograph is a potential responsive rather than a current responsivedevice, whereby. reactions from one tapping circuit or derivationthrough thebody upon another tapping circuit due to current flow aresub- 10 stantially eliminated.

The method of using a separate amplifier for increasing the actionvoltages drawn from the patient, apart from the fact of increasing theparts and apparatus required and consequently 15 the initial cost, hasthe further disadvantage that the amplifiers have to be adjusted toequal gain and matched both as ,to'amplitude and frequency response inorder to enable a comparison of both amplitude and phase relation of thein-= 20 dividual cardiographic curves obtained.

It is an object of the present invention to overcome the abovedifiiculty and to enable the use of a limited number of amplifiers forsimultaneously and independently recording a plurality of 25 actionvoltages drawn from different points of the human body.

With this general object in view the invention in one of its embodimentsinvolves the provision of a system wherein the input of a single ampli-30 fier is connected periodically and in rapid succession to a pluralityof input circuits or connectors applied to the points of the body of apatient from which the action voltages are to be drawn by means of aperiodic switching de- 35 vice, while at the same time the output of theamplifienis connected to the respective recording devices synchronouslywith the connection of the input circuit. In order to preserve the shapeof the curves recorded the switching fre- 40 quency is made considerablyhigher than the maximumfrequency of the heart beat curves or cycles, andfurthermore the recording devices are sufiiciently damped to eliminatethe eifect of transient potentials produced bythe switching 4:;operation. Since the frequency of the heart beat curves or cycles israther low, simple mechanical switching means such as oscillating orrotating contact devices may be employed for effecting the synchronousconnection of the input and 50 output circuits of the amplifier.

According to another embodiment of the invention especially adapted forsimultaneous recording of two action voltages, a single oscillograph isprovided with means for alternately 5 shifting its time axis from oneposition to another in synchronism with the switching of the actionvoltages to the input of the amplifier.

Accordingly, it is a further object of the invention to provide anelectro-cardiographic system for simultaneous and independent recordingof at least two action voltages drawn from different points of the humanbody by means of a single recording device and amplifier.

A further object of the invention is the provision of a system forrecording three or more action potentials drawn from the human body witha limited number of amplifiers with or without synchronous switching.

Another object is the provision of a simplified composite cathode rayoscillograph for simultaneously and independently recording a pluralityof input potentials hooked up according to a three-pole system upon asingle viewing and/or recording screen.

The above and further objects and features of the invention will becomemore apparent from the following detailed description taken withreference to the accompanying drawings forming part of thisspecification and wherein Figure 1 illustrates a simple diagram for amultiple electro-cardiograph system employing a single amplifier andsynchronous switching devices associated with the input and outputcircuit of the amplifier,

Figure2 shows a similar system to Figure 1 employing a composite cathoderay oscillograph constructed according to the invention, 1

Figure 3 shows a further modification of the invention for simultaneousand independent recording of several action voltages by means of asingle amplifier and oscillograph device,

Figure 4 illustrates a system for simultaneous recording of three actionpotentials drawn from a human body employing two amplifiers,

Figure 5 illustrates the composite deflecting arrangement for a multiplecathode ray oscillograph embodied in Figure 4, and

Figure 6 shows a system similar to Figure 4 for multiple recording ofthree action potentials.

Like reference characters identify like parts in the difi'erent views ofthe drawings.

Referring to Figure 1 of the drawings, there are shown at I, 2 and 3three tapping points from which action potentials are drawn from thehuman body by means of suitable connectors strapped to a patient. Thus.point I may correspond to the left arm; point 2 to the right arm; andpoint 3 to the left leg whereby the voltages obtained between thesepoints are represented by the connecting lines therebetween as shown atI, II and III forming a three-pole voltage triangle. There are furthershown at 4 and 5 a pair of oscillogra-phic recording devices forsimultaneously recording the action voltages II and III. The recordingdevices illustrated are of the electro-magnetic mirror type comprisingelectro-magnets and mirrors I2 and I 3, respectively, suspended onstrings passed through the magnetic field in a known manner and uponwhich light beams from a source 69 are projected to be variablydefiected by the oscillations of the mirrors in accordance with thecurrents applied to the magnet windings. The currents required forenergizing the magnets are supplied from a valve amplifier i. In orderto record the action voltages II and III simultaneously, the input andoutput circuits of the amplifier are each connected to the movablemembers of a pair of synchronously operated switching devices 1 and 8having cooperating contacts connected to the points I and 2 and to theopen ends of the energizing windings of the recording devices 4 and 5,respectively. In the example shown for recording the two action voltagesII and III, the tapping point 3 and the inner serially connected ends ofthe energizing windings of the recording devices 4 and 5 are grounded.The switching devices I- and 8 may be operated in any suitable mannersuch as by means of electromagnets energized by interrupted directcurrent impulses or the like produced in the example shown by anelectro-magnetic vibrator or buzzer 9.

In an arrangement of this type, it is seen that the voltage II betweenthe tapping point I and ground isapplied to the input of the amplifierin the position III of the switch I while in the position II of theswitch the action voltage III between the point 2 and ground isimpressed upon the amplifier. Simultaneously the correspondingoscillograph devices 4 and 5 are connected to the output of theamplifier in synchronism with the switch 8 and as a result bothoscillograph devices receive short current impulses the intensity ofwhich is proportional to the instantaneous potentials prevailing at thetapping points I and 2. The mirrors I2 and I3 are therefore deflected inproportion to the instantaneous variations of the action voltages H andIII and may serve to produce oscillographic records on a recording stripsuch as a photographic film or paper in a known manner. In order toprevent interference by the transient switching potentials, theoscillograph devices should be sufiiciently damped. Further details,such as the circuit connections, provision of supply voltages, etc., forthe amplifier 6 and the rest of the apparatus have been omitted from thedrawings for the sake of simplicity of illustration and disclosure andas not forming a part of the present invention.

The principle of the invention as illustrated by Figure 1 may beextended to the recording of all three action potentials. For thispurpose, it is advantageous to consider the three tapping points I, 2and 3 as the potential points of a three phase system subject to thegeneral law of such systems according to which the geometrical vectorsum of the three voltages at every instant is equal to zero; or in otherwords, the sum of the voltages between I and 3 and 2 and 3 must at anytime be equal to the voltage between I and 2. Thus by forming thedifferential voltage between the action voltages II and III the actionvoltage I may be obtained.

In place of electro-magnetic recording devices as illustrated, it isunderstood that any other oscillograph device may be used such as acathode ray or glow discharge oscillograph without departing from thespirit of the invention.

If a cathode ray oscillograph is used, the arrangement may be greatlysimplified by using a composite multi-beam oscillograph deviceconstructed according to the invention in place of three separateoscillograph tubes. In a device of this character only fourelectrostatic deflecting plates are required for effecting thedeflection of the three electron beams as illustrated in greater detailin Figure 2. In the latter there is shown a system for simultaneouslyrecording three action voltages between points I, 2 and 3 related toeach other according to a delta system by means of a single amplifierand a single composite multi-beam cathode ray oscillograph. The inputcircuit for the amplifier is substantially similar to that shown inFigure 1. The contacts 'ot :the;.s witching device fijiasso with. theoutput circuit or the. ampiiiierare con-.

1 concentrated.electron beam tr, pencil; The deflecting fieldforthe'centraliel'ectron beam is producedbetw'een' the-plates. and If!while the; de-

1 I ilecting:fleldsffor the outer electron beams are :produced between.the plates i6 and I9 and, the I plates i1 and-, respectively; Dependingon 1 the position of the switches land 8, plates liand I I are chargedto a potential proportional to" the ,instantaneouspotentials at thetapping p ints I I and}, respectively. [Inorder to prevent a dissipation of these charges vduringthe Switching I eriods by leakageand'to imposesuflicient dampof vacuum or gaseous discharge tubesoperating ing upon the deflecting systems; the plates liiand i! haveconnected; therewith suitable damping elements such as resistances 2|and condensers ,22 placed betweenthe plates and ground. It is seen thatin this manner an instantaneous .voltage corresponding to the actionvoltage II is impressed upon the plates iGjand l9, and a further voltagecorresponding to the action voltage III :is impressed upon the plates'l'I and 20, while a voltage proportional to the difierence between theaction voltages II and III corresponding to the action voltage I is setup between the plates l6 and l Tin such a manner that the three actionvoltages are simultaneouslyrecorded by the three electron beams. Thearrangement of the remaining parts of the cathode ray tube I8 such asthe luminescent screen-impinged by the electron beams to produceluminous recording spots and further means for producing a permanentrecord on a photographic strip are obvious to those skilled in the artand have been-omitted from the drawings and disclosure forsimplification. I In an analogousfmanner the action voltage I may beobtained by the difference between the currents supplied by theamplifier. if a current responsive recording device is used. In thelatter case, however, reactions and disturbances may occur under certaincircumstances with re-'- gard to the distribution or the current for whch reason an, electrostatically responsive recording device such as-acathode ray oscillograph is to be preferred in practice.

In place of electro-magnetically operated synchronous switching devicesany equivalent known arrangement may be used such as rotating contactdevices mounted upon the same shaft,.or electronic switching may beemployed by means substantially without inertia and controlled bysuitable alternating control potentials. It is further understood thatthe invention may be employed for'recording' more than three actionvoltages by means of a common amplifier by correspondinglyincreasing thenumber of switching contacts, as is readily understood.

Referring to Figure 3, there is shown an arfrangement for simultaneouslyrecording tw-o action voltages '(Iand H) though a single amplifier andby means of'a single recording device by alternately displacing the zeroaxis of the recording device synchronously withv the connection faiaai'o' elated or heinput' circuit 0'! the amplifier. In the exampleillustrated the action voltage I is connected to the in-put of theamplifier 26 in the position 23 ofa'vibrating switch 24 while the actionvoltage II is connected to the amplifier input in ,the'oppositeposition-25 or the. switch.

There. is further shown a means-such as a battery 21 for impressing anadditional di'fierentiating potential inseries with the action voltageII to effect 'a displacement of the zero or time axis on. themovingrecording strip 29 of the record'- ing device 28connected to the outputcircuit of the amplifier 26; Thus,-in the position 25 of the switch 24,the small additional voltage supplied by the battery 21 is alsoamplified in such'a mannerfl-that the recording beam of the indicatingdevice is displaced by a definite distance shownat 30. In this mannerthe two action potentials are 'diiferentiat'ed from each other bydisplacementoi the zero or time axis by an amount equal to thedeflection 30 on the recording strip 28. If

now the action voltages are superimposed aiternately and in rapidsuccession by the action of the vibrating switch 24 and at a frequencywhich is high relative to the frequency of the heart beat cycles orcurves to be recorded, cardiographic curves representing the variationsof the .action potentials l and 2 are recordedabove-the respective zeroor-time axes on the recording strip. 1 i

This simplemethod offers theadvantage over previous arrangements thatonly a single oscillographic device isrquired which does not require anysmoothing or damping elements due to the fact that the oscillograph isoperating continuously during both switching! periods in such a mannerthat the recording is independent of transient potentials between theswitch-v ing periods, since'only the instantaneous values are recordedwithout integrationas in the case of the previously describedarrangement. III" the switching is instantaneous as is true of mostmechanical switches, the luminous recording spot will change so quicklyto and from the two axes that the change will hardly be noticeable oronly a slight shadow 'be produced between the two cardiographic records.

While it is possible by an arrangement of this type to record only twoaction; voltages, the

system has great advantages due to its simplicity and etliciency wherenot more than two simultarieous records are required.

' In certain cases the switching may cause annoyance to sensiblepatients although weak capacitative charging currents may be impressedupon the patient'withou't harm if the apparatus is suitably designed andconstructed.

Inview of the distortions which may occur in an electro-cardiogram dueto the slightest irritation of the patient, it may be desirableincertain cases to eliminate entirely any potential variations in thepatient circuit and to effect a displacement of thezero axis of therecording device in another portion of the system. For this purpose asecond contact may be provided upon the movable member of the switch 24by means of which either the bias of an intermediate stage, the platevoltage or the magnitude of the output load resistance of the amplifier26 may be varied synchronously with the switching operation.Furthermore, the synchronous displacement of the zero axis may beefl'ected independently of the recording device such as by directing thelight beam of the oscillograph to an 1 auxiliary oscillating mirrormounted upon the tongue or movable member of the switch 24 in such amanner as to project the light beam to one zero axis in one position ofthe switch and to the other zero axis in the other switch position.Finally, if a cathode ray oscillograph is employed the zero point may bedisplaced magnetically by means of a small magnetic field coil with anenergizing circuit connected and disconnected by an additional contactassociated with the switch 24 to deflect the cathode ray periodically toand from the two time axes.

Referring to Figure 4 there is shown a system for recording three actionvoltages such as supplied from a triangular tapping system previouslydescribed whereby only two amplifiers without switching are required.The action voltages I and II are applied to a triple-cathode rayoscillograph 32 through the intermediate amplifiers 30 and 3|. Theelectron beams for the tube 32 are produced by means of cathods 33, 34and 35 surrounded by concentration cylinders 50, 5| and 52,respectively, or any other electron-optical concentrating systems. Thecathodes are further arranged opposite the openings 36, 3'! and 38 of acommon diaphragmatic anode or focussing electrode 53. In place of threeseparate deflecting systems for the electron beams, a compositedeflecting arrangement comprising four electrostatic deflecting plates39, 40, 4| and 42 arranged in parallel is provided similar to that shownin Figure 2. The electron beam produced by the cathode 33 is passedbetween the deflecting plates 39 and 40; the electronbeam produced bythe cathode 34 is passed between the deflecting plates 49 and 4|; andthe electron beam produced by the cathode 35 is passed between thedeflecting plates 4| and 42.

The operation of an arrangement of this type will be better understoodby disregarding the amplifiers 30 and 3|. In the latter case the voltagetriangle I, 2 and 3 is connected to the four deflecting plates 39 to 42in such a manner that point 3 is connected to the two outer plates 39and 42 which accordingly are at the same potential while the points and2 are connected to the two central plates 40 and 4|, respectively. As isseen, the voltage I is impressed upon the plates 39 and 40 and thevoltage II is impressed upon the plates 4| and 42 while the voltage IIIappears between the plates 40 and 4|. As a result, the three electronbeams are deflected by the three voltages and three simultaneouscardiographic records produced upon the luminescent screen applied tothe opposite end of the tube. In order to obtain a time axis for thecurves obtained, either a moving recording strip or rotating mirror maybe provided or the electron beams may be simultaneously deflectedlinearly in a direction at right angles to the deflection effected bythe plates," and 42. For the latter purpose according tg a furtherfeature of the invention a common/pair of time sweep deflecting plates43 and 44 (see Figure 5) extending over all four deflecting members 39to 42 are provided connected to a suitable source of sweep potentialpreferably of saw tooth shape' anodes of the amplifiers 45 and 46provided with load impedances 41 and 48 connected in series with theanodes and a common anode potential source 49. If both amplifiers are ofequal design and balanced to have equal gain only the voltage III willappear between the anodes whereby the central electron beam is deflectedin accordance with the variations of this voltage. The effect of thedirect current voltage drops produced by the impedances 41 and 48 areeliminated or balanced by connecting the outer plates 39' and 42 tosuitable tap points of the anode potential source to prevent initialdisplacement of the outer electron beams from their zero positions.Otherwise, the arrangement and operation according to Figure 6 issubstantially similar to that described in connection with Figure 4.

The arrangements and methods disclosed by the invention are not limitedto the recording action potentials drawn from a human body but as isunderstood equally apply to the amplification and/0r recording of anypotential variations related in accordance with a three-pole system.

It will be evident from the above that the invention is not limited tothe specific arrangements and methods shown and disclosed herein forillustration, but that the underlying inventive concept and novelprinciple is susceptible of numerous variations and modifications comingwithin the broader scope and spirit of the invention as defined in theappended claims.

I claim:

1. In an electro-cardiograph for simultaneously recording a plurality ofaction voltages drawn from different contact points of a patient, a'recording system, a common amplifier, switching means for successivelyand periodically connecting the input of said amplifier to the differentcontact points at a frequency substantially higher than the highestfrequency of the action voltages to be recorded, means operating insynchronism with said first means for separately recording theindividual action voltages as curves upon diilerent zero axes of therecording system, and damping means for said recording system toeliminate the effect of transient switching potentials upon the curvesrecorded.

2. In a device for simultaneously recording three action voltages of ahuman organism linked up with each other in the form of a three-polesystem, a common amplifier, means for periodically connecting the inputof said amplifier in rapid alternation to two of said voltages at a ratewhich is high relative to the variations of said action voltages, andmeans for recording the third of said voltages as a differential voltageof the two amplified voltages.

3. In an electro-cardiograph, means for simultaneously recording aplurality of action potentials drawn from different contact points of apatient, comprising a plurality of recording units each coordinated toone contact point for individually recording the action potentialstapped therefrom, a common'amplifier, switching means for periodicallyconnecting the input of said amplifier in rapid succession to theseparate contact points, further switching means for successively andperiodically connecting the output of said amplifier to the respectiverecording units in synchronism with said first switching means, thefrequency of said switching means being high compared with the frequencyof the action voltages to be recorded, and damping means for saidrecording units to eliminate the eiiect of tran- 4. In apparatus forsimultaneously recording a three alternating voltages linked up witheach other in the form of a three-pole system, a cathode ray tubecomprising means for producing three separate cathode rays and fourdefleeting members arranged side by side, each of said cathode rayspassing between two of said deflecting members, the two 7 outerdeflecting members being connected to one pole of said system and eachof the two inner deflecting members being connected to one of theremaining two poles of said voltage triangle, whereby each of said raysis controlled by one of said voltages. v

5.,Inv apparatus for simultaneously recording three alternating voltages,linked up with each other in the form of a three-hole system, a cathoderay device comprising means for pro- .ducing three separate cathoderays, a first deflecting arrangement comprising four electrostaticdeflecting plates arranged side by side, each of said cathode rayspassing between two plates of said deflecting arrangement, a seconddeflecting arrangement comprising a pair of deflecting platesperpendicular to and coextensive with said first deflecting arrangement,and means for impressing the potential at one pole of said system uponboth of the outer plates of said first deflecting arrangement and forimpressing each of, the potentials at the remaining poles of said systemupon one of the inner plates of said first deflecting arrangement,whereby all three cathode rays are individually deflected by said firstdeflecting arrangement in one plane by the voltages of said system andmay be simultaneously deflected by a voltage impressed upon said seconddeflecting arrangement in a perpendicular plane.

6. Means for simultaneously recording three alternating voltages linkedup with each other according to a delta circuit comprising a compositecathode ray oscillograph, means for producing three separate electronbeams therein and an electrostatic deflecting system comprising fourdeflecting plates arranged substantially parallel to each other, each ofsaid cathode rays passing between two of said deflecting plates, andconnections from both outer deflecting plates to one pole and from eachof the inner plates to one of the remaining poles of said deltascircuit.

'7. Means for simultaneously recording three alternating voltages linkedup with each other in a delta circuit comprising a composite cathode rayoscillograph, means for producing three initially concentratedsubstantially parallel electron beams therein, a common diaphragmaticfocussing electrode having three apertures each passing one of saidelectron beams, and an electrostatic deflecting system comprising fourdeflecting plates arranged substantially parallel to each other, each ofsaid electron beams passing between two or said deflecting plates, andconnections from both outer deflecting plates to one pole and from eachof the inner plates to one of the remaining poles of said delta circuit.

8. In a device for the simultaneous indication of three alternatingvoltages linked up with each other in the form of a three pole system,one of said poles being earthed, the combination of two amplifiers theinput circuit of each of which is connected to one of the two free polesof said three-pole system and a common cathode ray oscillographic devicecomprising means for producing three cathode rays, four deflectingplates in linear arrangement, each one of said three rays being flankedby two of said deflecting plates,

the two outer ones of said deflecting plates being earthed and the twoinner ones of said deflecting plates each being connected to one of saidtwo amplifiers, respectively.

9. In a device for the simultaneous recording of three alternatingvoltages linked up with each other in form of a three pole system, onepole of which is earthed, of a common amplifier, a com mon cathode rayoscillographic tube, means for producing three separate cathode raystherein, four deflecting plates in said tube in linear arrangement, thetwo outer ones of said deflecting plates being earthed, means foralternately connecting the two inner ones of said deflecting plates tothe input circuit of said common amplifier in rapid periodicity andmeans for synchronously connecting said amplifier to each of said twofree poles of the said three pole system.

10. In a device for the recording of more than one action voltage of ahuman organism, a com--v mon amplifier, recording devices respectivelyadapted for recording each of the action voltages, means forperiodically connecting the output of said amplifier in rapid successionto each of the said respective recording devices, and electric dampingmeans adapted to suppress the recording of the switching impulses topermit the simultaneous recording of said alternating voltages.

11. In a device for simultaneously recording three action voltages of ahuman organism linked upwith each other in the form of a three-phasesystem, a cathode ray tube comprising means including a common anode forproducing three separate cathode rays, four deflecting members for saidthree rays arranged parallel to each other and at equal distance fromsaid anode, the two outer deflecting members being connected to one poleof said three-phase system, and means including a common amplifier forperiodically connecting each of the remaining poles of said system toone of the inner deflecting members through said amplifier in rapidsuccession.

HANS ERICH HOILMANN.

CERTIFICATE OF CORRECTION.

Patent No. 2,1 ,1uo. October 11, 19

HANS ERICH HOLIMANN.

It is hereby certified that the above numbered patent was erroneouslyissued to the patentee, said "Hollmann" whereas said patent should havebeen issued to Radio Patents Corporation, a corporation of New York, asassignee, as shown by the record of assignments in this office; and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of November, A. D. 19

enry Van Arsdale (Seal) 7 Acting Commissioner of Patents.

